Yep, followed almost immediately by Repubs' switch to their "Southern Strategy" & southern white conservatives finding their message appealing...
Strom Thurmond led the defection from the Democratic party- you know, the guy with the longest filibuster on record, made against the Civil Rights Act...
Lyndon Johnson, who worked hard for passage, supposedly remarked that Dems had lost the South for a generation. He underestimated the virulence of southern conservative racism, however- it's been nearly 2 generations, and they're still staunch Repubs.
The party of Lincoln has fallen a very long way...